1. Field of the Invention
This invention relates broadly to endosurgical instruments. More particularly, this invention relates to an endosurgical instrument having an end effector which is radially movable.
2. State of the Art
Endoscopic surgery is widely practiced throughout the world today and its acceptance is growing rapidly. In general, endoscopic/laparoscopic surgery involves one or more incisions made by trocars where the trocar tubes are left in place so that endoscopic surgical tools may be inserted through the tubes. A camera, magnifying lens, or other optical instrument is often inserted through one trocar tube, while a cutter, dissector, or other surgical instrument is inserted through the same or another trocar tube for purposes of manipulating and/or cutting the internal organ. Sometimes it is desirable to have several trocar tubes in place at once in order to receive several surgical instruments. In this manner, an organ or tissue may be grasped with one surgical instrument and simultaneously cut with another surgical instrument while under the observation of the surgeon via the optical instrument in place in the trocar tube.
Various types of endoscopic surgical instruments are known in the art. These instruments generally include a slender tube containing a push rod which is axially movable within the tube by means of a manual actuator. One or more end effectors are coupled to the distal ends of the tube and the push rod so that axial movement of the push rod is translated to rotational or pivotal movement of the end effector(s). End effectors may take the form of scissors, grippers, cutting jaws, forceps, and the like. Endosurgical scissors usually include a pair of scissor elements (blades) attached to each other or a clevis by a pivot axle. These scissors may be single acting or double acting. In a single acting scissors, a first scissor element is held stationary relative to the distal end of the tube and a second scissor element is rotated about the pivot axle relative to the first scissor element. Endosurgical scissors are available in many forms, e.g. curved blades, hooked blades, angled blades, etc. However, most endosurgical scissors have relatively sharp distal ends and cut in the distal direction. These common design features of most endosurgical scissors present two disadvantages: (1) when locating the scissor blades at the surgical site, tissue may inadvertently be punctured or scarred by the sharp distal ends of the blades; and (2) since the endoscope and the scissors typically approach the surgical site from substantially the same direction, it is often difficult to see the tissue which is cut distally from the scissor blades. These disadvantages become quite problematic when the endosurgical cutting instrument is used in the vicinity of very delicate tissues such as the arachnoid membrane of the meninges.
Endosurgical grippers and forceps are similar in design to endosurgical scissors, but with a pair of gripping elements rather than a pair of scissor blades. The common design features of endosurgical grippers, forceps, and scissors present the disadvantage that they grip or cut in a distal direction. This tends to push the subject tissue away from the instrument which results in a possible failure to cut or grip the tissue.
U.S. Pat. Nos. 4,963,147 and 5,089,000 to Agee et al. partially address the problems encountered with conventional endosurgical cutting instruments. Both of these patents disclose a surgical instrument for the treatment of carpel tunnel syndrome. The cutting instrument disclosed by Agee et al. includes a hollow tube having a radial slit and a single cutting blade which is movable into and out of the radial slit by a push rod. The distal end of the tube is provided with a slotted rotatable pivot member through which the cutting blade is translated and rotated. In use, the cutting blade exits the radial slot in the tube with its sharp point angled in the distal direction and its cutting edge forming an obtuse angle with the proximal portion of the tube. The pivot member allows the blade to rotate slightly in the proximal direction as it exits the tube. The instrument is fairly complex and cutting is effected in a direction away from the tube. Thus, as the cutting blade is moved out of the tube, any tissue adjacent to the radial slot in the tube is exposed to the sharp point and cutting edge of the cutting blade.
A similar device is disclosed in U.S. Pat. No. 5,053,044 to Mueller et al. which concerns a cardiovascular catheter having a blade tip capable of making a radial incision. The blade is mounted inside the tip of the catheter and is rotatable out of the tip through a radial slot. Cutting is effected in a radially outward direction.
It is known to provide an endosurgical cutting instrument which cuts in the radially inward direction. These instruments are sometimes referred to as "retrograde" cutting instruments. U.S. Pat. No. 4,729,374 to Alfranca discloses a surgical instrument for transcholedochal papillotomy which includes a flexible coil with a single acting retrograde scissor end effector coupled to its distal end and a pull wire extending through the coil and coupled to the end effector. The end effector includes a fixed blade coupled to the distal end of the coil and having a blunt distal end and a movable blade distally hinged to the fixed blade. The distal end of the pull wire is coupled to the movable blade by a connecting rod which is hingedly connected to both the pull wire and the movable blade. A proximal handle with a displaceable spool moves the pull wire through the coil to open and close the movable blade. While the instrument may be effective in performing a retrograde cutting operation, it is mechanically complex and difficult to manufacture.
U.S. Pat. No. 5,112,346 to Hiltebrandt et al. discloses a retrograde cutting hook punch having a hollow tube with a push rod extending through it and a single acting end effector coupled to the distal ends of the tube and the push rod. The end effector includes a stationary member which is coupled to the distal end of the tube and a movable member which is distally hinged to the stationary member and hingedly coupled to the distal end of the push rod. The cutting hook punch is designed specifically for arthroscopic procedures and has a complex geometry. Like the cutting instrument disclosed by Alfranca, the cutting hook punch has at least two hinged couplings.